http://www.McaMotorClubCoverage.com
Check out this video and this pie chart to see why cars breakdown and the percentages as well.
Stats are from 2012:
Battery Boost 31.7%
Fuel Injection System 10.0%
Ignition System 9.9%
car breakdown
stats
towing
battery boost
tire change
roadside service
MCA
motor club
america
canada
puerto rico